Rainwater Harvesting with Cisterns for Landscape Irrigation - Florida

1. Rainwater Harvesting
with Cisterns
for Landscape Irrigation
Workshop/Presentation
Manual
First Edition
October 2009

2. Acknowledgements
The Rainwater Harvesting Initiative would like to thank everyone that cooperated in
assisting with this effort:
Developers
Ms. Pacia Hernandez, University of South Florida
Dr. Daniel Yeh, University of South Florida
Dr. Thomas Ruppert, University of Florida
Mr. Skip Wright, Florida Irrigation Society
Mr. Dave Bracciano, Tampa Bay Water
Reviewers
Ms. Esen Momul, University of Florida Institute of Food & Agricultural Sciences (IFAS)
Ms. Kathy Malone, University of Florida IFAS
Mr. Jeffrey Harris, Pasco County Utilities
Ms. Chris Claus, City of St. Petersburg Water Resources
Mr. Norman Davis, Hillsborough County Water Resources
Mr. Bob Peacock, Pinellas County Utilities
Ms. Jeannie Hayes, Pasco County Extension Florida Yards and Neighborhoods (FYN)
Ms. Wilma J. Holley, Pinellas County Extension FYN
Mr. Chris Dewey, Pasco County Extension FYN
Ms. Lynn Barber, Hillsborough County Extension FYN
Mr. Dale Armstrong, Pinellas County Extension FYN
Ms. Doris Heitzmann, Pinellas County Extension FYN
Ms. Dierdre Irwin, St. Johns River Water Management District
Ms. Melissa Roe, Southwest Florida Water Management District
Mr. Brent White, Southwest Florida Water Management District
2

3. First Edition
October 2009
Clearwater, FL
3

4. Table of Contents
1 Project Background and Definition
Defining the need………………………………………………………………………..1
Parties involved through initiative……………………………………………………..1
What elements were being developed by whom…………………………………….1
Drafting of materials…………………………………………………………...………..2
Review mechanisms…………………………………………………………………....3
How the program can be used………………………………………………………..3
2 How to Put on a Workshop
Florida Rainwater Harvesting Initiative linkage ……………………………………..4
Sponsor levels and charges…………………………………………………..…...…..4
What do the Sponsors receive in return for Sponsorship………………….……….5
Identifying a Minimum Number of participants……………………………..………..5
Workshop Agenda……………………………………………………………...……....6
Use of Workshop Presentation ………………………………………………………..6
Obtaining the Workshop Powerpoint Presentation…...……………………………..6
Revising Presentation Materials…………………………..…………………………..6
3 The Florida Rainwater Harvesting Initiative……………………………..…..7
4 Additional Future Coordination/Development Efforts……………………..8
Standard Cistern Presentation for Other Water Use Opportunities
Identifying Technical Research Needs
Identifying Legal and Code-related Research and Development Needs
Other

5. Appendices
Appendix A Workshop Presentation Notes Pages-
Appendix B University of South Florida Technical Report
Appendix C University of Florida Research Results
Appendix D Workshop Handout
ii

6. iii

7. 1 Project Background and Definition
Defining the need
In early 2009, Tampa Bay Water, a regional water supply Authority, began work
developing a Standardized Cistern Program Agenda, workshop structure and
presentation materials. The overarching goal of this effort is to eliminate barriers to
successful promotion of cistern systems for irrigation use in Florida and to link public
and private efforts.
The Tampa Bay region endured water supply shortage conditions over the three year
2006-2009 period. As a funding agency of the Florida Yards and Neighborhoods (FYN)
program in their tri-county area since 1994, they have witnessed the public’s interest in
installation of rain barrels and FYN’s rain barrel workshop program success. This is
also occurring through the 48 counties in Florida where the FYN programs are
instituted.
Parties involved through initiative
Tampa Bay Water provided funding to University of Florida and the University South
Florida to address these barriers and create a program that links the public to public
agencies and private industry. They also worked with Florida Irrigation Society staff on
this project.
What elements were being developed by whom
As part of Tampa Bay Water’s effort to conserve water, the agency worked with the
University of Florida, University of South Florida, the Florida Irrigation Society and
various cistern manufacturers and installers to develop a standard workshop for citizens
to promote installation and use of cisterns in the Tampa Bay region and across the state
so stored water can be used for irrigation, thus saving potable water.
The University of Florida was specifically tasked to determine what legal and code
analysis is required to adequately preclude program presenters from being liable for all

8. or portions of the workshop output. Local health departments were contacted
throughout the state in order to gage their reaction to the installation outdoor cisterns for
irrigation use. State and local ordinances were reviewed that may/may not deal with
cisterns.
The University of South Florida was tasked with helping to analyze technical and
engineering aspects of rainwater harvesting with cisterns. These included:
• Water quality considerations and issues associated with rainwater harvesting with
cisterns
• Engineering designs on sizing, storage and treatment to enable the appropriate and
reliable use of cistern water for intended applications
• Relevant operation and maintenance considerations for successful cistern use
• How rainwater harvesting with cisterns can be successfully integrated into an
existing water supply infrastructure
• Economic considerations for cistern strategies
The Florida Irrigation Society (FIS) assisted in the development of water use
requirements and sizing of cistern systems, while manufacturers and installers were a
part of the process of including a full-scale workshop with presentations, sponsors, and
links to actual product.
Drafting of materials
The University of South Florida coordinated with the University of Florida IFAS, FIS and
Tampa Bay Water in the elaboration of workshop materials that were to be used.
Specific issues and topics were identified as the most appropriate to present to the
public. Once a draft presentation was completed, dry-run workshops with members
from local governments, FYN (local and statewide), water management districts and
experienced cistern installers (invited) took place to collect further feedback on content
of presentation and workshop length.
2

9. Review mechanisms
Once the final workshop presentation is issued, further review, update and edit may be
necessary. Errata and modifications may to be submitted to the presentation steward
(Dave Bracciano, Tampa Bay Water) by email (dbracciano@tampabaywater.org) or in
writing.
How the program can be used
The workshop will be delivered as a package to the Florida Yards and Neighborhoods
(FYN) program throughout the region and state and would be part of FYN’s workshop
on rain barrels or a stand-alone workshop. In addition to educating citizens about
cisterns, the program would seek to connect interested parties with contractors and
businesses that can assist in designing and installing cistern systems.
3

10. 2 How to Put on a Workshop
Florida Rainwater Harvest Initiative Linkage
The Florida Rainwater Harvest Initiative (FRHI) initial goal is to add private industry
groups/associations that can use the workshop format to promote their industry and to
help insure that expertise is funneled back and forth between educators and workshop
attendees. It is not designed to circumvent training programs, continuing education unit
development, or modify standards developed by others.
This will allow individual workshop developers to contact these entities for potential
sponsors and potential business opportunities. It provides value to these private entities
by linking the public with association membership at workshops.
About a month before the workshop is to occur, the workshop developer should contact
either or both organizations to determine if they have members that would be interested
in sponsoring the upcoming rainwater harvest workshop.
Current representative organizations and contacts are;
American Rainwater Catchment Systems Association
Florida Representative: John Hammerstrom
johnhammer@bellsouth.net
Phone Number: (305)852-8722
http://www.arcsa.org
919 Congress Ave., Ste. 460
Austin, TX 78701
Florida Irrigation Society
www.fisstate.org
Jennifer Amarosa, Executive Administrator
administration@fisstate.org
Phone Number: (800) 441-5341/(813) 839-4601 Fax Number: (813) 839-4759
Address: P.O. Box 13502, Tampa, FL 33681
4

11. Sponsor levels and charges
Since it is anticipated workshops will be put on by Florida yards and Neighborhoods,
along with the potential for other government entity use, creating a sponsorhip process
that is consistent between FRHI entities is important Although public entities have
specific funding constraints through budgeting and oversight processes, monies are
generally needed to continue and expand programs.
Having workshop sponsors is a legitimate means to promote workshops and also
recoup costs for establishing them. In some instances, workshops may be located at
facilities that require cost recovery.
Workshop implementers have two means of sponsorship; funding provided directly the
entity in the way of a check or sponsoring a giveaway between all the sponsors at the
event (no exchange of funds with the government entity). It is generally recommended
that sponsorship levels be at least in the $50 range for 25-50 participants and at least
$100 for over 50 participants. Sponsorship should be based on available space for
sponsors to advertise along the side and/or back of the workshop location.
Workshop developers should decide which process works well for their entity before
sending out request for sponsors.
What do the Sponsors receive in return for Sponsorship
Sponsors get recognized during the workshop and thanked for their efforts.
During breaks and at the end of the workshop, the public will directly interact with
sponsors to determine if there is additional interest in pursuing installation of rainwater
harvesting systems. Materials provided during the workshop will give participants a
general checklist of items that are required for successful rainwater harvesting system
installation and linkage to irrigation systems.
5

12. Identifying a Minimum Number of participants
Based on discussion with Florida Yards and Neighborhoods coordinators in the Tampa
Bay region, it is expected that at least 25 participants should be signed up for the
workshop so sponsor levels can be secured as identified above. If less than 25
participants are expected, sponsors should be alerted prior to securing funding to insure
good will between the sponsors and workshop promoters.
In some cases, rain barrel workshops have had in excess of 100 people in attendance.
It’s generally recommended that workshops be kept to less than 100 people, unless
workshop presenters have experience dealing with large groups.
Workshop Agenda
A standardized agenda has been developed for the workshop. Modifications to the
agenda can be made but note the presentation is locked in presentation mode to insure
material and content integrity. Modifications to the agenda will generally not coincide
with material presented.
To suggest modifications to the agenda or presentation materials see Revising
Presentation Materials below.
Use of Workshop Presentation
The workshop presentation, located at
http://reservoir.tampabaywater.org/sites/frhi/default.aspx is locked in the presentation
mode. The cover slide is not locked so it can be modified to coincide with the
presentation date and location. Additionally, a slide with the workshop sponsors should
be provided. If entities have a logo, it is suggested you request an electronic version,
and use it in your presentation.
Obtaining the Workshop Powerpoint Presentation
The entire document will also be distributed through members of the Florida Rainwater
Harvest Initiative and can be requested by emailing Dave Bracciano, Tampa Bay Water,
6

13. at dbracciano@tampabaywater.org. All organizations that are distributing this
document are required to provide a master list of requesting entities, along with
pertinent contact information. This information will be used to determine actual
penetration rates for program implementation on an annual basis.
Revising Presentation Materials
On a quarterly basis, materials will be reviewed for modifications based on feedback to
dbracciano@tampabaywater.org. All comments specific to the presentation will be
addressed by the next quarter.
7

14. 3 The Florida Rainwater Harvesting Initiative
8

15. 4 Additional Future
Coordination/Development Efforts
Standard Cistern Presentations for Other Water Use Opportunities
Identifying Technical Research Needs
Identifying Legal and Code-related Research and Development Needs
Other
9

16. APPENDIX A

17. 1

18. 2

19. 3

20. Corrugated metal tanks in oblong shapes.
4

21. 5

22. 6

23. 7

24. 8

25. 9

26. 10

27. 11

28. 12

29. Our purpose in presenting this workshop…
Emphasis should be given that (1) these are basics – not comprehensive – of rainwater
harvesting and (2) focus will be only on irrigation as end use.
13

30. 14

31. Rainwater harvesting is the collecting and storing of rainwater. Collection is usually from
a roof, and storage is in a catchment tank.
15

32. Some of you may be rain barrel users. How many of you do that already? Good! Rain
barrels are a good start. That means that you are already doing your part in limiting
potable use for irrigation. You are also more careful of how you use the rainwater that
you collect.
However, you may have noticed that a rain barrel’s capacity is limited. It can only
capture the first 55 gallons of water captured from any roof. The rest is lost. With a
2000 sq ft roof, it is possible to collect over 22000 gallons of rainwater, yet only 660
gallons can be captured by a single rain barrel. That’s only 3% of available rainwater.
97% is lost!
16

33. Why harvest rain? Water is a finite resource. There is a very limited amount of
freshwater available for use. Most of it is trapped in ice and snow, 30% is underground
while less than 1 percent is in our lakes and rivers.
17

34. Others may be worried about current drought conditions and how this is affecting the
availability of water.
18

35. We read about limited water supplies every day. The impending rise of the cost of
potable water may be a result of limited supply.
19

36. There are environmental reasons to harvest rainwater. One reason is that it reduces the
amount of stormwater runoff that occurs. This could reduce flooding issues during
intense rain events. By collecting rain, we reduce the amount of water that is piped
through our storm sewers to wastewater treatment facilities.
20

37. Presenter: Interject reasons for capturing rain. Otherwise, here are some reasons.
Irrigation for landscape. Plants love rainwater and it is the ideal source for irrigation
when stored for summer usage. Rain naturally fertilizes plants (with nitrogen and sulfur)
while at the same time flushing out harmful salts from the soil. Rainwater does not
contain potential toxins and chemicals from water treatment plants or municipal
underground pipes.
Stored rainwater is available for irrigation when water restrictions for irrigation are
enforced and for emergency situations when municipal supplies may not be available or
sufficient (in the case of fire or hurricanes).
Rainwater harvesting systems are considered a valuable capital improvement to
g y p p
property. The return on investment varies from project to project but our clients have
found the independence gained from owning their own systems is priceless. For new
construction, the cost of the initial rainwater system is minimal when added to the
overall project loan.
At times, lack of available potable water supply has limited development. Conserving
potable water supply can facilitate development.
21

38. There are many uses for rainwater. Irrigation would be the application requiring the
least amount of treatment before use.
22

39. Where can we use harvested rainwater best?
Since irrigation consumes most of our potable water use, let’s start here.
********************************************************************
Irrigation remained the largest use of freshwater in the United States and totaled 137
Irrigation remained the largest use of freshwater in the United States and totaled 137
Billion gallons/day for 2000.
Since 1950, irrigation has accounted for about 65 percent of total water withdrawals,
excluding those for thermoelectric power.
The above info came from http://pubs.usgs.gov/circ/2004/circ1268/index.html
23

40. A good strategy would be to, not only conserve water, but also to use an alternative
water source (rainwater) for irrigation, and save our precious potable drinking water for
drinking and other indoor uses.
24

41. So today, we will be focusing on rainwater harvesting for LANDSCAPE irrigation.
25

42. 26

43. 27

44. Big or small, residential or commercial, the harvesting system will have these
components.
Trainer should mention each of these aspects and give a brief description of each. Each
part will be covered in more detail, including rain and its reliability.
part will be covered in more detail including rain and its reliability
28

45. 29

46. The roof (highlighted in yellow) is what is used as the catchment area. Its size dictates
how much rainwater can be captured.
30

47. Q: Does it matter what kind of roof I have?
A: No.
For irrigation purposes, roof surface is not an issue. For potable applications, this
For irrigation purposes roof surface is not an issue For potable applications this
becomes more of an issue. However, we aren’t addressing potable applications in this
workshop, …only irrigation applications.
However, the smoother the surface, the better for collection. For example, rain runs off
quicker and thus, ‘washes’ off any unwanted particles with less rain than other roof
types. Also, roof slopes affect how quickly roof surfaces get washed: steeper slopes are
‘washed’ quicker.
washed quicker
31

48. The next part of a rain harvesting system is conveyance.
32

49. Highlighted area shows location of the conveyance system: gutters and downspouts.
These move the captured water along to the cistern.
33

50. Something to keep in mind is that, if we are installing gutters to collect water that will
ultimately be stored, these need to be installed as a sealed system in order to keep
mosquitoes from entering. This is very important, because, if overlooked, it can become
a nuisance.
34

51. There are many factors that will affect the design of your home’s gutter system. Your
gutter professional will be best suited to address each of these. However, know that the
dimensions and shape of your roof will determine the size of your gutters, the number
of downspouts needed and where you will install proper hardware so that spillage can
be minimized and every possible drop of rain is captured.
be minimized and every possible drop of rain is captured
35

52. Keeping limbs and leaves away from catchment area and from clogging conveyance is
important in keeping cistern water quality pure.
These products reduce maintenance needs while preventing debris from entering the
cistern.
cistern
Pollen pods can be filtered out as well.
36

53. 37

54. Filtration should occur between the downspout and the tank. The ultimate goal is to
remove impurities before they reach the tank. What impurities? (Go to the next slide)
38

55. 39

56. There are several kinds depending on your budget‐but you need to have this!
There is the downspout filter, (extreme left) which has a fine filter screen. The next filter
is a strainer type filter. Both of these require regular cleaning (like lint basket in your
dryer!) in order for it to function efficiently.
dryer!) in order for it to function efficiently
The next two shown are examples of the ‘self cleaning type’. The benefit here is that less
maintenance is required. The downside is that you lose some water in the process
and…they are more expensive.
40

57. This is used so that (a) water can be extracted from the top of the cistern and (b) any
floating particles can be filtered. Are they filtered or just precluded from being
withdrawn till you get to the end?
41

58. This involves smaller contaminants that weren’t filtered previously, like bird dropping
residue.
42

59. Slide is animated!
43

60. 44

61. If we are serious about having only the cleanest water in the cistern, then, in essence,
we need to have a first flush device at each collection point (picture this in your mind: as
you collect water at each downspout, a 'first‐flush' device needs to be at the end of each
downspout) OR, all the collected water needs to be flushed ‐ bigger volume ‐ prior to
entering cistern. Depending on the size of catchment area, this volume can be
entering cistern Depending on the size of catchment area this volume can be
considerable, and burying the 'first‐flush' tank may be a consideration.
45

62. 46

63. Read definition #1
The cistern or storage tank is generally the most expensive aspect of the system.
47

64. UV protection refers to not allowing any sunlight into tank. Sunlight is creates desirable
conditions for algae growth. Therefore, black tanks are recommended.
Tank life are subject to conditions they are exposed to, but can last 30 year or more.
Manufacturer s can provide a more accurate lifespan for tanks.
Manufacturer’s can provide a more accurate lifespan for tanks
Both above and below ground tanks require stabilization and/or tank pad. Consult with
tank installer or engineer regarding structural requirements. This may also include
hurricane straps/bracing.
48

65. Cisterns are by no means ‘one size fits all’. There are different shapes and materials for
different needs and applications. They can also be custom made.
***This is a good place to show the 5 minute video on how metal tanks are put
together. The link is located on the last slide of this section.***
49

66. You will notice that cisterns have a lot pipes going in and out of them. This configuration can vary, but
generally there will be an inlet, an outlet, an overflow and drain valve.
A manway is also necessary for maintenance/cleaning. Never go inside alone or without a plan on how to
get out.
Inlet, outlet and overflow are self explanatory. Trainer should call these out.
Inlet, outlet and overflow are self explanatory. Trainer should call these out.
Overflow: Engineering drainage design may need to come into play here. Common sense dictates for
overflow to be directed away from tank/buildings where volume of water won’t cause erosion, flooding,
carry organic material (especially if animals are present) into wells or water sources, cause standing water
for long periods (mosquito breeding), etc. Over flow can be directed towards in place drainage system or
can also be allowed to percolate into the ground via french drain, etc.
Overflow outlets can be configured in different ways. If the overflow outlet draws from the bottom, it
should be vented to prevent siphoning. Overflow outlets and vents should be equipped with a fine mesh
screen to prevent mosquito entry.
Anaerobic/Sediment zone is located in the bottom 6” or so of the tank. Here is where the ‘dirtier’ water
and sediment tends to collect. Avoid drawing water from this portion of the tank.
A hose bibb or drain valve is needed in order to drain the tank if needed. Bibb should be elevated 6” or
so. Solids tend to accumulate at the bottom so elevating will help avoid clogging.
The floating suction filter will allow water to be extracted in the cleaner area of the tank. Particles either
settle at the bottom of the tank or float on top. Thus, the filter on the end of the hose will filter the
remainder of the particles before sending the water to the irrigation system.
Important to make sure all openings are sealed properly to avoid (1) mosquito infestation (2) animal
intrusion and (3) children from entering the cistern.
Tank should be placed on a level, stable foundation. This may consist of gravel or concrete pad.
FACT: Water weighs 8.34 pounds per gallon. A 1000 gallon cistern can weigh up to 8340 gallons when
full. Imagine what would happen if an unstable tank tips over.
50

67. 51

68. Pumps are necessary to pump water from cistern through irrigation system. Some drip
irrigation systems may not require a pump.
52

69. What a pressure tank does:
Protects and prolongs the life of the pump by preventing rapid
cycling of the pump motor
Provides water under pressure for delivery between pump cycles;
and
and
Provides additional water storage under pressure to assist the
pump in meeting the total demands of a system if the pump is
incapable of supplying the required capacity.
Pump sizing is best left to the experts. It is best to seek
professional help in this department.
53

70. So, What does all this cost?
54

71. DRAFT 9/23/2009
55

72. DRAFT 9/23/2009
56

73. 57

74. Very simple, but regular, maintenance is required.
58

75. 59

76. We have covered the basics of a rainwater harvesting system. Ready for a quiz?
60

77. Each question/answer comes up after mouse click. After question appears, optional
‘jeopardy’ music can be played (to avoid uncomfortable silence) by clicking ‘speaker’
icon at bottom right of slide.
61

78. 62

79. 63

80. 64

81. 1

82. Passive irrigation – what it is, how it conserves water, and how it can work for you!
2

83. 3

84. Demand Method ‐ Based purely on anticipated water needs
***************************************************************
Water balance method (1) Maintain a monthly balance, (2) Start with an assumed
Water balance method – (1) Maintain a monthly balance (2) Start with an assumed
volume (3) Add volume captured (4) Subtract monthly demand (5) Evaluate size and
affordability of storage capacity.
Major storm method – This method is used in order to capture every drop available at a
major storm event (or every available drop during wettest month).
major storm event (or every available drop during wettest month).
Provides
Pro‐ Minimum cistern volume needed to capture rainfall for this size storm
Con‐ Not based on water usage
What is the quick calculation method? A ‘quick and dirty’ way of calculating water
quantities.
ii
4

85. How to calculate rainfall capture potential
This means, how much rain can be collected on the roof that you have.
5

86. To calculate how many gallons of water that can be collected, use this basic formula:
Area of Roof (generally in square feet)
Rainfall (inches)
Rainfall (inches)
Then multiply to obtain amount in gallons.
6

87. The area of catchment surface is only as big as the footprint of your house. Think of
how a raindrop sees your roof as it makes its way down. Whether it is slanted or flat, it
will fall within this area. That is the area we are concerned about. So, you can multiply
the length and width of roof area, or use the square footage of building.
***********************************************************************
*******************************************************
For more information see http://www.harvestingrainwater.com/rainwater‐harvesting‐
inforesources/water‐harvesting‐calculations/
7

88. One ‘chunk’ of rain….
One inch deep x 1 square foot = 0.623 gallons of rainwater collected
8

89. 9

90. 10

91. 11

92. Ever bake a batch of cookies? Even though the recipe states that you can bake a dozen,
it’s never exactly that much, right?
Well, try as you may, you will probably not collect every drop of water from your roof.
You will lose water due to evaporation from your hot roof, spillage or overrunning of
You will lose water due to evaporation from your hot roof spillage or overrunning of
your gutters, or other factors. So, to compensate, lower factor down to .5 gallons/square
foot per inch of rain.
******
In case someone asks: Why remember .623 when you tell them to use 0.500 ?
0.623 is the CONVERSION FACTOR. 0.5 is not.
0.5 takes into account water losses in the system.
0.5 = 0.623 (conversion factor) * 0.8 (runoff coefficient)
***********************************************************************
***************************************
Runoff coefficient of 0.80 is a conservative number from Civil Engineering Reference
Manual for the PE Exam, Eighth Edition, by Michael R. Lindeburg, PE, page A‐43.
12

93. In case someone asks: Why remember .623 when you are using 0.500 ?
0.623 is the CONVERSION FACTOR. 0.5 is not.
0.5 takes into account water losses in the system.
0.5 = 0.623 (conversion factor) 0 8 (runoff coefficient)
0 5 = 0 623 (conversion factor) * 0.8 (runoff coefficient)
******************************************
Instructions to Presenter: Arrow takes you to slide where conversion factor with water
losses is broken down by units for those who require further explanation.
13

94. This is where we calculate how much water is used in irrigation.
14

95. The formula for calculating water demand, in this case: how much water will be used
for irrigation, is very similar to our first formula for calculating water collection potential.
We consider the area to be irrigated (in square feet), the conversion factor of 0.623. The
only difference is that, instead of inches of rain, we use something called ET rate.
15

96. Check out the definition‐ Evapotranspiration (ET), defined as the evaporation from the
soil surface and the transpiration through plant canopies (Allen et al., 1998), is the
exchange of energy for outgoing water at the surface of the plant (Allen et al., 2005).
The above definition may be too ‘high tech’ for the layman, so simplifying it – as in slide
– may be best.
16

97. So, as an example, let’s calculate how much water is needed to irrigated 2000 square
feet of St. Augustine sod in Florida. Let’s calculate it for the month of January using 2”
of water needed for that month.
17

98. Remember this number? Use this here.
18

99. Voila! This is how much water is necessary to irrigate 2000 square feet of St. Augustine
in Florida for the month of January.
19

100. 20

101. Vendors have websites that simplify the computation of rainfall potential and water use
demand, as shown above. Note maximum monthly capture is approx. 5200 gallons;
while maximum monthly usage at 3200 gallons. Owner must decide if they want to
purchase enough that will be used, or a little bigger to capture max roof yield. Max roof
yield option will allow to store that left over amount for drier months.
yield option will allow to store that left over amount for drier months
This is a good recommendation:
We need to size this based on warm dry season irrigation needs and mention drought
conditions. Assume 50% of normal rainfall for dry period (say April and May).
Sizing should be captured at 50% of normal rainfall versus demand required. Deficit
will require supplemental supply, reductions in use or modification to landscapes.
21

102. To what degree is rainwater reliable as a main source of water supply?
Rainwater varies from year to year
May need alternative source‐ BUILD YOUR SYSTEM TO MEET YOUR
LANDSCAPE NEEDS IN A FLORIDA DROUGHT
Alternative Water sources
AC Condensate
Shallow Wells
22

103. DRAFT 9/23/2009
This graph shows the amount of water (in inches) for irrigation for a St. Augustine lawn
per month (shown in green) and the average rainfall for our area (the blue line). As can
be seen, there are times during the year that there is more than sufficient rainfall for our
lawns (white space between blue line and green shading), but other times there isn’t
enough rain (shown where blue line dips into green shading).
enough rain (shown where blue line dips into green shading)
23

104. DRAFT 9/23/2009
During the last 3 years, we’ve been experiencing less than average rainfall.
In order to show this, the average yearly rainfall has been adjusted by 50%. The dashed
blue line shows this as the ‘adjusted’ yearly rainfall. This is just a conservative number
j y y j
(factor of safety of 2), assuming we only receive half of the average rainfall.
24

105. DRAFT 9/23/2009
At this point, it may seem that it is impossible to irrigate using rainwater exclusively.
If we were to consider the required amount of water to irrigate St. Augustine turfgrass
and contrast that with the adjusted rainfall, it would look something like this.
j , g
Click – It would seem that we now have a monthly rainfall deficit, every single month.
Relying totally on the rain for irrigation would not be sufficient.
However, what if we captured the same amount of inches of rainfall on our roofs using a
cistern? What would happen then?
cistern? What would happen then?
25

106. DRAFT 9/23/2009
What would happen is that we could actually capture the same number of inches of
rain…and store it until we needed it?
Suppose we had a 2000 sq. ft. catchment area and 500 sq. feet of St. Augustine turf to
pp q q g
irrigate. This graph shows how many gallons of rainwater can be collected and how
much is needed for irrigation.
Now we can clearly see parts of the year where there is a surplus and others where
there is a deficit – or need – of irrigation water. In this particular instance, a surplus
occurs between June and late September. A small Deficit occurs in March through late
May.
26

107. DRAFT 9/23/2009
What size cistern is needed?
Here, green represents the harvested rainwater used for irrigation and the blue, the
rainwater that is stored in the cistern.
The deficit that occurs in April and May, which accounts for about 600 gallons, should be
added to total amount needed in April. The minimum capacity required during April is
1,915 gallons (1,308 + 407 + 200) to make it through the ‘dry period’ of April and May.
This happens to be the maximum amount of volume stored throughout the year, as no
other month requires this much volume. For this particular case, an adequately sized
cistern is one whose capacity is approximately 2,000 gallons.
27

108. Adjust how much you intend to water. Maybe just water front yard and flower bed. Let
the back go.
28

109. Conservation can be a big part of your overall plan in using rainwater for irrigation.
One good method for irrigation can be passive irrigation. What is that?
Should we build in FYN concepts here? Yes!
Should we build in FYN concepts here? Yes!
29

110. Presenter to explain the difference between these to diagrams. Rather than letting
water drain to street to storm drains, capture water by grading yard to automatically
capture some rain in beds and where trees are planted. Mulch these areas so that
water isn’t quickly evaporated.
These are recommended for new development. In attempting to incorporate this
method in existing development, danger lies in (1) flooding your neighbor and (2)
disturbing or damaging buried utilities (cable, telephone, water, sewer) or existing
swales. Therefore it is discouraged.
************Good time to show Movie by Brad Lancaster on Passive
************G d ti t h M i b B dL t P i
Irrigation*********************************************
http://www.youtube.com/watch?v=k9Ku_xpyLK4&feature=related
30

111. Rain garden allows runoff to re‐enter the soil, and is a place where drought‐tolerant
plants are used to provide an aesthetically pleasing landscape. Work with your FYN
program to help determine how to do this.
31

112. Switch to drip irrigation. This allows water to be delivered directly to roots and avoids
water to be lost to evaporation as in spray irrigation. In many cases pressure
requirements can also be low!
32

113. There is no need to be afraid of the quality of rainwater.
33

114. Rainwater is very clean.
34

115. 35

116. How much treatment is needed?
Non‐potable uses
Minimal treatment
Filter remove sediments, etc. runoff from roof (as mentioned earlier)
Filter – remove sediments etc runoff from roof (as mentioned earlier)
Potable (not addressed here)
Significant treatment
Filtering
*******************************************
When the water is to be used just for landscape irrigation, only sediment filtration is
typically required. Sustainable Construction Green Building Design and Delivery
typically required. – Sustainable Construction – Green Building Design and Delivery –
Charles J. Kibert
36

117. Condensate recovered from residential applications can vary between 3‐5 gallons per
day. Factors that influence condensate recovered is load size, load efficiency, interior
relative humidity,
37

118. 38

119. 39

120. These guides are very useful and available online.
40

121. 41

122. Tell us why these sites are good to view?
ARCSA (American Rainwater Catchment Systems Association) website has a wealth of
information.
Harvesting Rainwater.com is easy to read information
Harvest H2O has many articles on rainwater harvesting
There are others too. Surf around!
Speak to vendors that are here sponsoring , and use our presentation as a starting point
on purchasing your system.
42

123. 43

124. 44

125. 45

126. 46

127. 47

128. 48

129. 49

130. APPENDIX B
2

131. Rainwater Harvesting With Cisterns for
Landscape Irrigation
Pacia Hernandez*
University of South Florida, Department of Civil & Environmental Engineering, Tampa, FL, USA
*
Florida Rainwater Harvesting Initiative
David Bracciano*
Tampa Bay Water, Clearwater, FL, USA
Thomas Rupert*
University of Florida, Levin College of Law, Gainesville, FL, USA
Skip Wright*
Newberg Irrigation Inc., St. Petersburg, FL, USA
Daniel H. Yeh, Ph.D., P.E., LEED AP*
University of South Florida, Dept. of Civil & Environmental Engineering, Tampa, FL, USA
ABSTRACT
The purpose of this paper is to present the technical content and sources reviewed in the
development of the Florida Rainwater Harvesting Initiative’s public training workshops. Said
workshops are to be presented by FYN (Florida Yards and Neighborhoods) program either as a
substitute or in conjunction with the Rain Barrel Workshops throughout Florida.
This paper describes the major parts of a rainwater harvesting system, the function of each, and
what components may be necessary specifically for landscape irrigation use. Estimating
irrigation demand and calculating cistern sizing based on demand are also considered.
INTRODUCTION frozen as ice and snow, or below ground.4 Not
An ample water supply meant the survival of only are fresh water sources limited, but drought
many ancient civilizations. The inhabitants of conditions, together with increasing population
the ancient middle- eastern city of Petra were and the lack of availability of potable water make
able to control their water supply by the use of it even more valuable. Several regions in the
dams, cisterns and water conduits. They United States, including the Tampa Bay area,
developed the ability to store water during are currently experiencing drought conditions
prolonged droughts. Their plentiful supply of that are expected to persist.
water put them on the map as a hub for the
east-west trade route.1 For the ancient Mayans In some parts of Florida, irrigation can account
living in the city of Sayil, water was quite scarce. for over 50% of a single family’s water use.
The water table lay 200 feet below ground which Therefore, a logical first step in solving the water
motivated them to discover how to collect and shortage problem is mitigating potable water use
store rainwater. Archaeologists have discovered for irrigation. This can be accomplished by
that each household had at least one educating citizens and businesses to reduce
underground cistern.2 Even below the streets of their use of potable water for irrigation and
the famous ancient city of Alexandria lies a substituting an alternative water source, such as
system of cisterns.3 rainwater. This strategy is gaining popularity in
the Tampa Bay region. For instance, local
Today, water’s scarcity is also making it a very citizens are on a waiting list in order to benefit
valuable resource. Only 2.5% of the world’s from Hillsborough County’s Extension Office free
water is freshwater. Of that 2.5%, 0.3% can be Rain Barrel Workshops.5
found in our lakes and rivers. The rest is either An important lesson that rain barrel users learn
in harvesting their own water is that the typical
55 gallon rain barrel captures only a fraction of
1
(The Jordan Tourism Board, 2008)
2 4
(NOVA, 2008) (United Nations Environment Programme (UNEP))
3 5
(Dunn) (University of Florida, 2008)
Rainwater Harvesting With Cisterns for Landscape Irrigation 1

132. the available rainwater that falls on their roof. • Homeowners have greater water
For example, (see Figure 1) a 2,000 square foot independence, a reliable source for
roof can capture almost 23,000 gallons per year, irrigation, decreased water bills, a capital
while a mere 700 is captured by rain barrel. improvement to their property
That is only 3% of the available rainwater; nearly • Developers can count on ‘diverted’ water
97% is lost. This is a motivating factor in moving from irrigation to be available for new
towards larger storage medium, such as residential or commercial development
cisterns.
Though the focus of this research is for the
Another indicator of the public’s acceptance of application of landscape irrigation (non-potable),
rainwater harvesting is the growing number of there are also many other uses for rainwater:
buildings that use cisterns. Rinker Hall at the outdoor applications, such as washing cars,
University of Florida in Gainesville has an 8,000 replenishing pools and fountains, indoor uses
gallon cistern to collect rainwater for toilet such as toilet flushing, clothes washing and
flushing. Similarly, Learning Gate Community showering, industrial processes, and, with
School in Lutz has a 10,000 gallon system for proper filtration and treatment, even for drinking.
toilet flushing. Cisterns are not only for schools, Different design criteria, regulations, costs and
or for toilet flushing. A residential home in St. health concerns will apply for systems other than
Petersburg, Florida stores 1,000 gallons of those intended strictly for landscape irrigation.
rainwater by cistern for landscape irrigation.
THE RAINWATER HARVESTING SYSTEM
There are five main parts to a rainwater
harvesting system (see Figure 2):
• Catchment Area (roof)
• Conveyance (gutters/downspouts)
• Pretreatment (filters, first-flush)
• Storage (cistern)
Based on a 2,000 sq. ft. • Distribution (to irrigation system)
catchment area with adjusted
rainfall quantities.
Catchment Area
The catchment area can consist of mostly
anything. Island dwellers use tarps attached to
trees to capture rainwater. However, if
harvesting rainwater for use relative to a
building, using the existing roof surface makes
more sense.
Catchment surface material is not of primary
importance when the intended use is irrigation.
For potable applications, however, this becomes
more of an issue because of the possible
leaching of contaminants into the water that is
collected (such as from asphalt shingles).
Material is also an issue when considering how
much is to be captured (system efficiency), as
Figure 1 – Rainwater Capture by Rain Barrel
well as how quickly any given rain event
‘washes’ particles from the roof’s surface. In
BENEFITS AND USES OF RAINWATER other words, the slicker the material is, the
There are many benefits to harvesting rainwater:
quicker debris is washed off and the greater the
• Environmental reasons include reducing
quantity of clean water that can be captured.
stormwater runoff (by creating on-site
stormwater retention)
The size of the catchment area determines the
• Using less energy and reducing green harvesting potential for the intended application.
house gases from reduced potable water
This aspect is addressed under the topic of
system demand
System Sizing.
Rainwater Harvesting With Cisterns for Landscape Irrigation 2

133. regularly (like the filter in a clothes dryer - after
every cycle); others are virtually self-cleaning,
and require minimal maintenance. The self-
cleaning types have two drawbacks: they (1)
tend to lose water in the process and (2) are
more expensive.
Another level of filtration that is commonly used
is the ‘roof-washer’ or a first-flush device. Its
purpose is to capture the first part of a rain
event, with the intent of diverting the dirty or
contaminated water (e.g. bird dropping residue)
from entering the tank. In doing so, the stored
water will remain relatively free from
contamination and will minimize the frequency of
cleaning the interior of the tank. Since there are
many variables that can affect how quickly a roof
Figure 2 – Anatomy of the System is ‘washed’ with a rain event (e.g. intensity and
time since previous rain event, slope and
Conveyance porosity of catchment surface), there are
Conveyance consists of gutters and disagreements on how much should be flushed.
downspouts. This part of the system moves the Some sources say 10 gallons for 1000 square
captured water from the roof, through gutters feet of catchment surface6. Others say more.
and downspouts, down to the storage tank or Another school of thought subscribes to no
cistern. Various materials are used with the flushing at all. This method may be used where
most desirable being the aluminum seamless rain is scarce and collecting every possible drop
type. Seamless is desirable for two reasons (1) is more important than how clean the water is.
less water is lost if it is water tight and (2) less Water quality is improved post-storage, by
opportunity of mosquitoes to penetrate the adding a filtration system (a combination of a
system and infest the stored rainwater. As with series of filter cartridges with ultraviolet light or
standard gutter system design, the size and other treatment as needed and required by local
slope of the catchment surface determines the agencies) prior to use.
number of downspouts required and the location
of downspouts relative to the gutters. The One final level of filtration that is commonly used
distance from ridge to eave also determines the with cisterns for irrigation is one that is within the
size of the required downspouts and the tank itself: the floating suction filter. This filter is
frequency a downspout is needed. attached at the end of a hose which floats on the
water surface and collects the water near the top
A common issue with gutters is that leaves and of the tank. With very few particles floating on
twigs interrupt the flow of water, requiring the surface (most of the particles accumulate at
frequent cleaning. Gutter accessories minimize the bottom of the tank), suctioning water from
the frequency of maintenance, with the ultimate the top of the tank would provide the cleanest
goal being the collection of the cleanest water water possible.
possible for storage.
Storage
Pretreatment The cistern is the storage component of the
Pretreatment (or filtration) usually occurs rainwater harvesting system. It is available in an
between the downspout and the storage tank, infinite amount of colors, sizes, shapes and
removing impurities before they reach the tank. types of materials. If a pre-fabricated tank is
Debris and contaminants can consist of leaves, selected, it should be black, a dark color, or UV
twigs, dust or particles (from shingles or resistant, such that no light can penetrate it
pollution), and possibly bird droppings. (sunlight penetration encourages algae growth
within the tank). Both above and below ground
Pre-filtration screens are screened baskets that
hold back larger debris (such as leaves, twigs, 6
(Texas Water Development Board, Third Edition,
and pollen pods). Some must be cleaned 2005, p. 8)
Rainwater Harvesting With Cisterns for Landscape Irrigation 3

134. type cisterns are available. Underground tanks pump needs to kick on and build up pressure in
require excavation costs and more structurally the system for use. For the pump, this would
sound walls, which may be more expensive than mean short on-off cycles until demand is met,
installing a tank above ground. As far as costs and thus shortening the pump’s life. A pressure
are concerned, the cistern is usually the most tank system would provide water (under
expensive component of the rainwater pressure) between cycles, eliminating both the
harvesting system. constant cycling and wait times between cycles.
Consulting a plumbing professional is highly
Any given cistern (above or below ground) will recommended in selecting the best equipment
require an inlet, an outlet, an overflow and a for each application.
manway (see Figure 3). The overflow will be
positioned close to the top of the tank in case SYSTEM SIZING
collected rainwater exceeds the cistern’s There are several methods for sizing a cistern:
capacity. Overflow should be routed away from • Water Balance Method
the tank (either by piping or site grading) to a • Major Storm Event Method
location that can accommodate the overflow • Demand Method
volume and will not cause erosion or flooding. A
flap valve (or similar device) should be used at The water balance method is similar to
this opening to keep out unwanted animals or balancing a checkbook. Using the size of the
insects. The manway is essential to allow catchment area, the amount of potential
access to the inside for cleaning/servicing the rainwater capture would be calculated and
tank. It should be safely secured at all times to added as the amount coming ‘in’ to the system,
keep out animals and children. The cistern is subtracting monthly demand (amount needed for
considered a confined space; appropriate safety irrigation as amount coming ‘out’), and
procedures should be followed. evaluating the size and affordability of storage
capacity.
The major storm event method sizes the cistern
by assuming to collect all available rainwater
during the heaviest storm event. For example, if
the largest storm event has been measured to
be approximately 4 inches, then the catchment
area is multiplied by the conversion factor and
runoff coefficient. Said volume would be the
cistern size.
Since the Tampa Bay region does not
experience long periods of drought (it rains most
months), the most appropriate method is the
Figure 3 – Anatomy of a Cistern demand method. It would determine tank size
according to the amount of anticipated water
Some recommended options for the tank could demand. Rainfall capture potential is calculated
include a: by a simple formula:
• Hose bibb - for ease in emptying the tank
• Turbulence calming device - since particles Equation 1: A x R=G
and debris tends to settle at the bottom of
the tank, this would minimize mixing when Where
water enters the tank. A = Catchment area of building (in square feet)
R = Inches of Rainfall (inches)
Distribution G = Gallons of Rainwater collected (gallons)
Ultimately, the system will need to be connected
to the irrigation system. A pump is needed in
order to provide sufficient head for water to be Size of Catchment Area
distributed to the desired location. The down Step one would be to calculated the rainfall
side to a regular pump is that water is not potential for the catchment area available.
‘ready-to-go’ at a moment’s notice, but rather Calculating the area is as simple as multiplying
Rainwater Harvesting With Cisterns for Landscape Irrigation 4

135. the length times the width of the roof. The key is can vary from 0.7 – 0.958. Because of this,
in calculating the roof footprint, regardless of another rule of thumb is used:
how the roof is sloped.
Rule of Thumb
(which includes runoff coefficient for losses)
One inch of rain falling on one square
foot of catchment area = 0.5 gallons of
rainwater collected.
The above rule of thumb reflects a C-Coefficient
of 0.8. A more accurate estimate for capture
potential would be:
Equation 3: A x R x 0.5 = G
Figure 3 – Roof Footprint 7
2000 sq. ft. x 2 in x 0.5 = 2,000 gallons
Amount of Rainfall
There is a rule of thumb that is used to quickly Water Use Demand
calculate rainfall potential: The same general equation applies with regards
to water demand, with only one difference:
Rule of Thumb instead of rainfall, ET (evapotranspiration factor)
is used.
One inch of rain falling on one square
foot of catchment area = 0.623 gallons Equation 4: A x ET x 0.623 = G
of rainwater collected.
ET is the sum of evaporation and transpiration,
which is basically the amount of water a plant
needs. Each plant type requires different
We can think of a ‘slice’ or ‘chunk’ of rain that is amounts of water in order to survive. ET rates
one inch thick and one square foot in area also vary geographically and over time.
equaling 0.623 gallons. Basically, this number is A good source for ET rates for the Tampa Bay
a conversion factor that converts inches per region is http://www.floridaturf.com/ , which are
square foot to gallons. The equation now based on the Steward and Mills, 1967 study.
becomes The ET rates for the coveted St. Augustine turf
grass is shown in Figure 4.
Equation 2: A x R x 0.623 = G
Reliability of Rainwater
For a 2,000 square foot catchment area and 2 The reliability of rainwater for irrigation use
inches of rain, depends on several factors: sufficient quantity
of rainfall, efficiency of the system, and
2000 sq. ft. x 2 in x 0.623 = 2,492 gallons meticulousness of the harvester. The amount of
rain that falls on any given region varies from
However, 100% of the rain is not generally year to year9. Even though predictability is not
captured. There are factors, such as entirely possible, estimates can provide a good
evaporation, the over-running of gutters, water sense of how much rainwater to expect to
loss due to filtration and/or first-flush, which capture.
reduces the captured amount. The runoff
coefficients (C-Coefficients) for roof surfaces
7 8
(Texas Water Development Board, Third Edition, (Michael R. Lindeburg, 2001, pp. A-43)
9
2005) (NCDC, 2007)
Rainwater Harvesting With Cisterns for Landscape Irrigation 5

136. Water use for irrigating the St. Augustine turf. With the use
Month (inches) of a cistern, captured rainwater could facilitate
January 2 the use of rainwater whenever needed,
February 2.5 especially during periods when rain is scarce.
March 3.4
April 4.2 More than enough rain
May 5.2
June 4.3 Not enough rain
July 4.8 (typical)
August 4.8
September 3.9
October 3.4
November 2.5
December 1.9
Total 42.8
Means of five years'
observations of
evapotranspiration on St.
Augustinegrass turf, Plantation,
Florida (Stewart and Mills, 1967). Figure 6 – Turf Water Requirements and
Figure 4 – ET Rates Adjusted Yearly Rainfall
Immediately following is an analysis of rainwater During a drought period, the amount of rainfall
harvesting potential paired with irrigation can be significantly reduced. To illustrate, an
demand for a small plot of St. Augustine turf. ‘average’ rainfall year can be reduced by 50%.
This would produce a conservative ‘adjusted’
rainfall rate for calculating the anticipated rainfall
More than enough rain
amount (see Figure 6). Deficits would now exist
throughout the year.
Not enough rain
(typical) Consider a 2,000 square foot catchment area
that is to be used to irrigate 500 square feet of
St. Augustine turf (in Florida). Rainwater is to be
collected during a drought year in a cistern.
What is the minimum sized cistern that can
accommodate the required demand?
Figure 7 shows the irrigation demand and
collection potential relationship volumes. It
Figure 5 – Turf Water Requirements and
clearly depicts which times during the year
Average Yearly Rainfall
yields a surplus and where there is a deficit – or
need – for additional water. In this particular
Figure 5 shows the amount of water that is
instance, a surplus occurs between June and
required to irrigate a St. Augustine lawn per
late September. A small deficit occurs in April
month and the average rainfall for the Tampa
through May.
area10 . It is apparent that there are times during
the year that there is ample rainfall for a typical
St. Augustine lawn, while at other times there is
not. Deficits generally occur during March
through late May, and again during October and
November. It seems that the timing of rainfall
only rainwater could be captured (or harvested)
during the rainy season (June through
September), there would be sufficient rainwater
10
(NOAA Satelite and Information Service, 2008)
Rainwater Harvesting With Cisterns for Landscape Irrigation 6

137. More than enough rain
(typical)
Not enough
rain
Figure 9 – Average Cistern Costs by Material
Figure 7 – Yearly Rainwater Collection Type 11
Potential
Economic Considerations
In viewing how water is used and stored in the The most costly portion of the initial investment
cistern, the method for sizing a cistern becomes (including design, components and installation)
more obvious. Figure 8 depicts the same data is the cost of the cistern. Costs for the cistern
shown in Figure 7 only shown as water levels can vary depending on material type, above or
within the cistern. The deficit that occurs in April below ground (needs to be more structurally
and May, which accounts for about 600 gallons, sound) and relative distance between site and
should be added to total amount needed in April. manufacturer (shipping). The cistern:
The minimum capacity required during April is installation cost ratio is approximately 60:40 12.
1,915 gallons (1,308 + 407 + 200) to make it Therefore, a complete 2,000 rainwater
through the ‘dry period’ of April and May. This harvesting system (that would serve the
happens to be the maximum amount of volume example considered earlier) could cost between
stored throughout the year, as no other month $2,000 to $3,500 (see Figure 10). Costs can be
requires this much volume. For this particular reduced by taking other water conservation
case, an adequately sized cistern is one whose measures. Consider the size of tank and
capacity is approximately 2,000 gallons. material selection.
Figure 8 – Cistern Rainwater Levels Figure 10 – Estimated Costs for a 2,000
Gallon Rainwater Harvesting System13 14
As a side note, most months show a surplus that
is stored in the cistern for the following month. A
11
larger cistern or adding additional cisterns could (Texas Water Development Board, Third Edition,
2005, p. Table 6.1)
yield greater rainwater potential. 12
(Water Environment Research Foundation, 2009)
13
(Texas Water Development Board, Third Edition,
2005, p. Table 6.1)
Rainwater Harvesting With Cisterns for Landscape Irrigation 7

138. Irrigation Options rates have not been officially established and
There are other methods for irrigating that are therefore anticipating collection potential is
efficient. Passive Irrigation/Collection is a difficult. An approximate amount of condensate
rainwater collection technique that involves that can be collected can vary between 3-5
contouring the landscape in a manner in which gallons per day for every 1000 square feet. This
water is collected in depressions where trees or amount alone is not significant enough in
flower beds are located, eliminating the need for residential applications to be an alternative
manual or mechanical irrigation. Brad source.
Lancaster, a well known rainwater harvester
who lives in the Sonoran Desert, is an avid Component Reliability
promoter of this rainwater collection technique. The reliability of the equipment or components
A very informative video on this topic can be of the system depend mostly on regular
viewed at inspections and maintenance. Manufacturers
http://www.youtube.com/watch?v=k9Ku_xpyLK4 provide general information on average life and
&feature=related. recommended maintenance. Anticipated
replacement life for some system parts:
Retrofitting irrigation system to be of drip type
can also be a water saving option. The amount Filters
of water used is minimized and precious water is • Cartridges for potable systems: 3 to 6
applied at the roots rather than being sprayed months
into the air using traditional lawn sprinklers. • Roof washing types: (see manufacturer’s
specifications)
The application of Florida Friendly Landscaping
techniques can be most beneficial. Drought Pumps
tolerant plants can reduce the amount of turf and • Approximately 3 years (see manufacturer’s
irrigation required in order to keep a beautiful specifications)
landscape. Information can be found at
http://www.swfwmd.state.fl.us/yards/ . • With a pressure vessel: generally longer
Water Quality than pump alone (see manufacturer’s
The quality of collected rainwater has always specifications)
been a concern, as is how it would change over Tanks
time. Generally, rainwater is the ‘cleanest’ • Approximately 20 to 30 years, depending on
source of water. It does not come in contact material and environmental conditions (see
with the soil (as groundwater does), therefore it manufacturer’s specifications)
does not contain harmful bacteria, dissolved
salts or heavy metals that would need to be Operation and Maintenance
treated or removed. The quality of harvested Maintenance costs for a non-potable use system
rainwater would rely mostly on the level of care can be kept low, if the owner performs the
and meticulousness that the harvester maintains required maintenance.
in the system.
Some maintenance responsibilities include:
The end use of the water would determine the
applicable level of treatment that is required. • Check for debris in tank (tank should be
EPA’s “Managing Wet Weather with Green cleaned out about once a year)
Infrastructure Municipal Handbook, Rainwater
Harvesting Policies” (Table 3) suggests pre- • Inspect gutters and downspouts regularly
filtration and first-flush diverters as minimum (remove debris)
water quality treatment options for outdoor uses.
• First flush bypass (check drain holes are
An additional source of high quality water that is clear for proper function)
readily available during hot, humid summer
months is AC condensate. This water source is • Inspect downspout seals and entrances
of sufficiently high quality that it can be stored in (check for leaks)
the cistern along with rainwater. Production
14
(Water Environment Research Foundation, 2009)
Rainwater Harvesting With Cisterns for Landscape Irrigation 8

139. Barriers and Incentives Some suggestions would be to:
There are no rules currently in place that would
prohibit the installation rainwater harvesting • Research the topic. Educate yourself on the
systems in the Tampa Bay area. Non-potable subject.
rainwater applications have fewer code
requirements and associated costs than potable • Visit demonstration sites.
ones.
• Speak to vendors, irrigation/rainwater
Public agencies and organizations in the Tampa harvesting professionals.
Bay area do not currently offer any monetary
incentives for those wanting to install rainwater • Start small. Improvements and additions
harvesting systems in their homes. There are could always be made at a later time.
places in Florida where incentives are offered.
For instance, the Florida Keys Aqueduct SUGGESTED READING
Authority is currently offering monetary incentive Texas Manual on Rainwater Harvesting
to residents who convert their decommissioned
septic tanks into cisterns for rainwater EPA’s Managing Wet Weather with Green
harvesting. 15 Infrastructure Municipal Handbook Rainwater
Harvesting Policies
CONCLUSION
Using rainwater as an alternative water source Rainwater Harvesting for Drylands and Beyond
for irrigation is a very logical first step in by Brad Lancaster
conserving potable water. In educating the
public about harvesting rainwater, a second Rainwater Collection for the Mechanically
lesson is learned in practice: Rainwater users Challenged by Suzy Banks
learn to be more cautious with water usage.
Putting together a rainwater harvesting system
for irrigating landscapes is not rocket science.
The components are simple enough for
homeowners to put together on their own with
some education on the topic.
Systems can become complex depending on
system size, intended use, and location. An
excellent source of technical and professional
help in building or developing said systems is
ARCSA. ARCSA (the American Rainwater
Catchment Systems Association) provides
informal publications and networking for
rainwater users. Their website is at
www.arcsa.org.
Since the issue of conserving potable water and
using alternative water sources (such as
rainwater) is gaining momentum throughout the
country in recent months, there is ample
information at their reach: online sources,
irrigation/rainwater harvesting professionals, and
demonstration sites.
15
(United Press International, Inc., 2009)
Rainwater Harvesting With Cisterns for Landscape Irrigation 9

140. BIBLIOGRAPHY Maintenance Guidelines. Retrieved 5 12, 2009, from
Allen, E. (1980). How Buildings Work: The Natural Hawaii Rainwater Catchment Systems :
Order of Architecture . New York: Oxford University http://www.hawaiirain.org/downloads/catchment.php
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